The present invention relates generally to printing technologies, and more specifically relates to anilox rollers and means to overcome the problem of anilox scoring.
Anilox inking printing systems are used in flexography and lately also in offset printing. Reference is now made to FIG. 1, which illustrates an anilox inking system. An anilox inking system 5 comprises an anilox roller 10 that picks up ink 12 from an ink chamber 14, Anilox roller 10 has an engraved surface, which delivers a fixed amount of ink to an adjacent form roller 16. The ink, which covers form roller 16 with a thin uniform layer, is then transferred to a plate cylinder 18. Anilox inking system 5 further comprises at least one doctor blade 20, which remove excessive ink from anilox roller 10.
One of the problems associated with anilox inking systems is scoring. Scoring means the formation of scores on the surface of the anilox roller. The scoring occurs when a small particle gets stuck in the gap between the blade and the anilox roller and scores the surface during operation. Therefore, the scores are usually perpendicular to the rotation axis of the roller. The particle may be chipped of a wall of an engraved cell or may reach the blade in another way. As a result, the scoring may occur more frequently in offset printing since an offset anilox roller has thinner, more breakable, walls than a flexography anilox roller. The number of engraved cells per unit length on offset anilox rollers may be 280 to 600 cells per inch.
The inking delivery system transfers ink layers having even distribution between successive rollers and to the plate cylinder. The scores on the anilox roller may, however, cause an uneven ink distribution on the rollers and plate cylinder resulting in undesired artifacts on a printed image. These artifacts may reduce the overall print quality to an unacceptable level. Thus, there is a need for a method for the reduction or elimination of the anilox roller scoring marks.